A camera module used in a camera-equipped mobile phone, a digital camera, a security camera, or the like has an integrated structure of, for example, an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS); a wiring substrate having terminals and a light-transmitting unit such as glass; a cover body holding the image sensor and the wiring substrate; a light concentrating unit configured of a lens, a lens barrel, and the like; and a lens holder holding the light concentrating unit.
FIG. 18(a) is a sectional view illustrating a schematic configuration of a camera module 100 disclosed in PTL 1. FIGS. 18(b) to 18(e) are plan views illustrating the planar shape of an air vent groove G that is formed in a cover body of the camera module 100 illustrated in FIG. 18(a).
As illustrated in FIG. 18(a), the camera module 100 includes a light concentrating unit 120 and an imaging unit 110. The light concentrating unit 120 is a lens unit that includes a lens holder 122 and a lens 121 fixed to the lens holder 122.
A wiring substrate 111, an image sensor 113 mounted on the wiring substrate 111 with an adhesive 112, a light-transmitting unit 117, and a cover body 114 covering the wiring substrate 111 and the image sensor 113 are disposed in the imaging unit 110. The image sensor 113 and the light-transmitting unit 117 are disposed below the lens 121.
The cover body 114 is fixed on the wiring substrate 111. The end portions of the light-transmitting unit 117 are fixed to the cover body 114 with an adhesive 116.
An opening 114a is disposed in the center of the cover body 114, and the light-transmitting unit 117 is arranged on the opening 114a. Consequently, the light-transmitting unit 117 and an internal space 118 surrounded by the cover body 114 and the wiring substrate 111 are formed in the imaging unit 110.
When the internal space 118 is sealed, a rise in temperature accompanies thermal expansion of air in the internal space 118, and a crack or the like starting from a joint portion of each member constituting the internal space 118 may be produced. In addition, a change in temperature or a change in atmospheric pressure may cause blurriness in the light-transmitting unit 117 with influence of gas or ions produced from the adhesives 112 and 116 or the like.
Therefore, in the camera module 100, an air vent groove G is disposed in the cover body 114, and the internal space 118 and the outside of the cover body 114 are connected through the air vent groove G and a gap 119. The planar structure of the air vent groove G, for example, has a shape that is bent in the form of an angle or a circle as illustrated in FIGS. 18(b) to 18(d) or a shape in which a circular recess portion GH is disposed as illustrated in FIG. 18(e).
According to PTL 1, in the case of not considering shrinkage of the adhesive 116, the depth of the air vent groove G ideally has the minimum value (for example, 0.01 to 0.1 mm) that achieves both of two objects of emitting air existing in the internal space 118 and preventing intrusion of a foreign object from the outside.
However, according to PTL 1, in the case of considering shrinkage due to the adhesive 116 flowing into the air vent groove G, approximately 0.015 mm to 0.040 mm, for example, is appropriate, and the length of the air vent groove G is preferably set to, for example, 0.2 to 1.0 mm and the width of the air vent groove G to, for example, 0.1 mm to 0.5 mm.
FIG. 19 is a sectional view illustrating a schematic configuration of a camera module 200 disclosed in PTL 2.
As illustrated in FIG. 19, the camera module 200 has a solid-state image sensor 220 mounted on a substrate 210, a lens holder 230 holding a lens 231 and mounted on the substrate 210, and an air-permeable resin 212 filling the inside of a through hole 211 formed in the substrate 210. The solid-state image sensor 220 is sealed in the inside of an air-cavity 240 formed by the substrate 210 and the lens holder 230.
According to PTL 2, even if the ambient temperature of where the solid-state image sensor 220 is placed rises and thereby heats air in the air-cavity 240 and causes pressure inside of the air-cavity 240 to rise by the pressure of the expanded air, the expanded air is dispersed through the air-permeable resin 212. Thus, according to PTL 2, a rise in the pressure of the air-cavity 240 in which the solid-state image sensor 220 is sealed can be reduced, and a positional relationship between the solid-state image sensor 220 and the lens 231 can be accurately maintained.
FIG. 20(a) is a sectional view illustrating a schematic configuration of a semiconductor device 300 disclosed in PTL 3. FIG. 20(b) is a plan view illustrating a schematic configuration of the semiconductor device 300 illustrated in FIG. 20(a). As illustrated in FIGS. 20(a) and 20(b), the semiconductor device 300 includes at least a package main body 303 in which a cavity 302 capable of accommodating a semiconductor element 301 is formed.
An air vent unit 305 that connects the cavity 302 to the outside is formed in the package main body 303 in a state where the semiconductor element 301 is accommodated in the cavity 302 and sealed with a lid member 304. The air vent unit 305 is a through hole having a bent structure.
Thus, the semiconductor device 300 disclosed in PTL 3 can prevent a foreign object from entering the cavity 302 with the air vent unit 305.
The package main body 303 may be in a stacked form formed by stacking a plurality of layers. According to PTL 3, the air vent unit 305 can be easily and efficiently formed by, for example, forming a hole in a plurality of layers configured of an organic-based material (a high molecular weight polymer or the like) and integrating the layers in a stacking manner.
FIG. 21 is a sectional view illustrating a schematic configuration of a camera module 400 disclosed in PTL 4. As illustrated in FIG. 21, the camera module 400 includes an image sensor 402 mounted on a substrate 401, an infrared removing filter 403 having one side thereof facing the image sensor 402, a lens 404 facing the other side of the infrared removing filter 403, and a cylindrical hollow case 405 mounted on the substrate 401 to accommodate the infrared removing filter 403 and the lens 404 and to cover the image sensor 402.
An internal space 406 is formed between the image sensor 402 and the infrared removing filter 403. The internal space 406 is connected with an air vent 407 exposed to the outside. A porous cylindrical elastic body 408 is disposed on the peripheral portion of the image sensor 402. The cylindrical elastic body 408 is in elastic contact with one side of the infrared removing filter 403. Accordingly, the cylindrical elastic body 408 supports the infrared removing filter 403.
The internal space 406 is surrounded by the cylindrical elastic body 408. Thus, according to PTL 4, the cylindrical elastic body 408 removes dust included in external air flowing into the internal space 406, while connecting the internal space 406 to the external space.
The surface area or the thickness of the cylindrical elastic body 408 can be sufficiently secured. Thus, a material that is unlikely to cause clogging even after long-term use thereof can be used.
According to PTL 4, condensation or the like can be securely prevented by maintaining a connected state between the internal space 406 and the external space for a long period. Furthermore, according to PTL 4, the cylindrical elastic body 408 supports the infrared removing filter 403 inside of the cylindrical case 405. Thus, the infrared removing filter 403 is in a state of having a position thereof determined even without being bonded to the cylindrical case 405, and an assembly step of bonding the infrared removing filter 403 to the cylindrical case 405 can be omitted.